186 MR. H. A. SMITH ON ANIMAL LIFE 



nate and exist, that I thought it might be interesting to 

 find out to what extent it could be present in water con- 

 taining free acids, and also to notice how far free acids 

 prevented its origination. 



The animals upon which the experiments were tried 

 were the Rotifers {Rotifer vulgaris) . These were obtained 

 by washing a certain amount of air in distilled water and 

 exposing the washings to the air in a small wooden vessel, 

 which was kept lightly covered. Five days elapsed before 

 they came to perfection. 



The method of procedure was very simple : — One litre 

 of air in the neighbourhood of an alkali-work was washed 

 in a glass vessel with ioo cubic centimetres of pure dis- 

 tilled water ; this was then transferred to a small wooden 

 vessel and allowed to stand in the laboratory, at a tempe- 

 rature which remained nearly constant at 6o° F. Pre- 

 viously, however, the total amount of acidity had been 

 obtained, which equalled 0*065 grm. per litre. This was 

 calculated in the first place as sulphuric acid. 



After having stood five days, the liquid presented a very 

 lively appearance when viewed under the microscope, and 

 the Rotifers seemed in a very active condition. The total 

 acidity was now raised, by the further addition of sul- 

 phuric acid, to 0*084 grm. per litre ; but there was no per- 

 ceptible difference in the appearance of life. On raising 

 the acidity still higher* (to 0*097 grm. per litre) a very 

 decided difference was observed. The appearance of the 

 liquid was no longer clear, but became of a light brown 

 shade; whilst the Rotifers were apparently unwilling to 

 move, and when any disturbance took place in the fluid 

 their motion was very sluggish. This seemed to be a defi- 

 nite point in the action of the acid. Small " clots M of 

 vegetable matter also became visible, presenting a charred 



* In every case, in these experiments, on the addition of acid, the liquid 

 was allowed to stand an entire day before further addition. 



